Power press



Aug. 28, 1934. K. KECK 1,971,937

POWER PRESS Filed Jan. 11. 1930 2 Sheets-Sheet l Patented Aug. 28, 1934 UNITED STA rowan rnsss Karl Keck, Goppingen, Germany, assignor to firm: L. Schiller Aktiengesellschaft, Golllfl ten,

Germany Application January 11, 1930, Serial No. 420,271 In Germany January 16, 1929 5 Claims. (Cl. 78-40) My invention relates to power presses, with a crank or an eccentric for reciprocating the slide. In presses of this. kind as heretofore designed the tool is rigidly connected with the slide and in consequence thereof the stroke of the slide must be comparatively large and not less than twice the length of the blank. For in order to permit insertion of the blank into the lower die and removal from such die, the tool in its position must be disposed at a distance above the lower die which is equal to the length of the blank plus a clearance, and the stroke from the initial position to the bottom of the die is obviously equal to twice the length of the blank plus the clearance. The large stroke not only increases the size, and consequently the initial cost, of the press but also reduces the economy of its operation. I

It is an object of my invention to eliminate this drawback of the existing presses, and to reduce the stroke to the single length of the blank plus clearance. To this end I provide a movable tool support on the slide of the press, and means for displacing the support and forflxing it in a given position with respect to the slide.

In a preferred embodiment of my provide in the slide a cylinder for a hydraulic piston the stroke of which is equal to the length of the blank plus clearance, and provide means for advancing the piston in the slide so that the tool moves into contact with the upper end .of the blank, or nearly so, before the'slide is started on its downstroke. I now fix the piston with respect to the slide by closing the inlet and outlet ports of the cylinder, and lower the slide. It is obvious that with the tool support advanced for the length of the blank plus clearance, the stroke which the slide must perionn is only equal to the single length of the blank, andnotto twice its length.

A press d si ned in accordance with my invention is much smaller and cheaper than the usual press with its large stroke. The amount ofenergy required for operating the tool support in the slide, for instance, controlling the valves of a hydraulic piston, is quite small.

It is another object of my invention to provide automatic means for controlling the tool support in the slide. To this end I provide a dog on the frame of themes which is able to actuate the control mechanism, and means for returning the mechanism into its initial position after the dog has released it. g

It is'still another object of my invention to invention I- cessive pressure in the system. To this end, in connection with a hydraulic piston, I provide a safety valve and preferably connect with the safety valve 9. device for automatically throwing out the drive of the press when a given pressure is exceeded.

In the drawings aflixed to this specification and forming part thereof presses having 'a hydraulic piston for operating the tool support are illustrated diagrammatically by way of example.

In the draw ngs Fig. 1.is an elevation of the slide at the lower die,

Fig. 2 is a section on the-line 22 in Fig. 1,

Figs. 3, 4 and 5 are diagrams, in section on the line 3-3 in Fig. 1, illustrating various positions of the control valve for the piston,

Fig. 6 is an elevation of a complete press in which electrical means are provided for throwing out the drive of the machine when excessive pressure occurs in the system, and

Fig. 7 is an elevation of a press having mechanical means for the same purpose.

'Referring now to the drawings and first to Figs. 6 and "l, 36 is the frame of the press, 3'7 is a pulley or other driving element on the shaft 38, 31 is a pinion which is free to rotate on the shaft, 30 is a friction clutch part which is connected with the pinion, 29 is the mating clutch part which is splined on the shaft 38, 32- is a gear wheel which is keyed on the crank or eccentric shaft 39 of the press and meshes with the pinion 31, 40 is a pitman or an eccentric shaft to which reciprocation is imparted upon rotation of the shaft 39, 6 is a slide attached tothe lower end of the element 40, and 41, 41 are a pair of guides between which the slide 6 is fitted to reciprocate.

Referring now to Figs. 1 to 5, 1 is the table of the press which is supported in the frame 36, 3 is a lower die for forging a tube, 2 is the blank, 4 is a bushing at the'lower endof the die, and 5 is an opening in the bushing the diameter of which is equal to the outside diameter of the flnishedtube. The slide 6 is connected with the 100 spherical lower end of the element 40. 8 is the tubular upper die which is secured to the lower face of the slide 6, 'I is a punch which is fitted to slide in the lower die 8, its diameter being "equal substantially to the inside diameter of the bushing 4, 9 is a piston rod to which the upper end of the punch 7 is secured, and 10 is a piston at the upper end of the rod which is fitted to reciprocate in a cylinder of the slide 6.

' p vi a Safety flpp flw r ex- Liquid under pressure is supplied to the cyl- 1 inder from a supply pipe 11. The supply pipe 11 is connected with the casing of a four-way valve 12 which in turn is connected with an upper and a lower port 13 and 14, respectively, of the cylinder, and with a discharge pipe 15. 24 is a safety valve which is connected with the upper port 13, and 16 is a pressure gauge which is connected with the space above the piston 10.

17 is the spindle of the valve 12 which, as shown in Fig. 2, extends to that side of the press which is opposite the casing of the valve 12; 18, 19 is a bell-crank lever which is fitted on the outer end of the spindle 1'7, 20 is a spring secured to the slide 6 of the press at 20 at one end and to the short arm 19 of the bell-crank lever at its other end, and 21 is a dog, secured on the frame 36, for controlling the bell-crank lever 18, 19. I

The operation of my novel press is as follows:

Figs. 1 and 2 show the piston 10 at the upper end of its stroke and Fig. 3 shows the corresponding position of the four-way valve 12. The arms of the bell-crank lever 18, 19 are indicated in dot-and-dash lines in Figs. 3-5, and the position of the .arms in Fig. 3 corresponds to that shown in Fig. 1. In this position the passage 23 of the valve 12.connects the port 13 above the piston with the discharge pipe 15 and the port 22 connects the port 14 below the piston with the supply pipe, 11. The punch 7 is retracted into the upper die 8 so that the blank 2, which is redhot, may be inserted between the faces of the dies 8 and 3, as shown in dot-and-dash lines in Fig. 2. The blank is then lowered into the lower die 3, whereupon the valve 12 is rotated into the position illustrated in Fig. 4 by hand. In this position the passage 23 connects the upper port 13 with the supply pipe 11 and the passage 22 connects the lower port 14 with the discharge pipe 15. Liquid under pressure is now admitted above the piston 10 while the liquid below the piston is expelled and the piston descends until the end of the punch '7 bears on the blank 2. When this position has been attained the valve 12 is rotated into the position Fig. 5 in which the passages 22 and 23 break all connections. The valve is held in this position by hand or by mechanical means. The piston is now rigidly connected with the slide 6 by the entrapped liquid. The press is started by throwing in the clutch 29, 30, and the slide 6 descends with the punch '7 as a single unit. The punch penetrates the blank 2 until the upper die 8 seats on the top of the blank.

Shortly after-the slide has been started the short arm 19 of the bell-crank lever on the spindle 17 is engaged by the dog 21 and held in the position shown in Fig; 5 so that it need not be held by hand all the way. When the slide 6 has completed its downstroke the short arm 19 is released by the dog 21 and the spring 20 returns the bell-crank lever 18, 19 into its initial position, in which, as shown in Fig; 3, the upper port 13 is connected with the discharge pipe 15 and the lower port 14 is connected with the sup- It may occur that excessive pressure builds.

up in the system, for instance, if. the blank is not hotenough. In cases of this kind the safety valve 24 is operated and relieves the pressure. Mechanisms for cutting out the drive of the machine in combination with the safety valve 24 are illustrated in Figs. 6 and 7.

Referring first to Fig. 6, 24 is the safety valve the connections of which with the cylinder in .the slide 6 have been omitted. The liquid under pressure is admitted to the body 42 of the safety valve at 43, and discharged at 44. The safety valve is provided with the usual spring 45 and a spindle 46 which controls a switch 25. 26 is a contact in the circuit 47 of an electromagnet 27 which is energized when the safety valve 24 is opened and, through the medium of its spindle 46 and the switch 25, closes the circuit 4'7 at 26. The armature 48 of the electromagnet is now attracted and through the medium of a doublearmed lever 28, throws out the friction clutch 29, 30. 7

Referring now to Fig. 7, the valve 24 by its spindle 46 operates adetent 33 which controls one arm of a weighted bell-crank lever 34, 35. The arm 34 of the bell-crank lever is operatively connected with the sleeve of the clutch part 29 and when the valve 24 is raised from its seat under excessive pressure the spindle 46 descends, causing the detent 33 to release the arm 34 whereupon the weighted arm 35 throws out the clutch.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occurto a person skilled in the art.

In the claims afiixed to this specification no selection of any particular modification of the invention is intended to the exclusion of other modifications thereof and the right to subsequently made claim to any modification not covered by these claims is expressly reserved.

I claim:

1. A power press comprising a slide, mechanical means for reciprocating said slide, a die, a cylinder in said 'slide, a piston adapted to reciprocate in" said cylinder, 9. tool secured to said piston so as to partake in its reciprocation, said cylinder having a passage at its upper and at its lower end, means for displacing said tool and for fixing it in a given position with respect to said slide and including: a fluid supply, a fluid discharge, mechanism for alternately connect ing one of said passages with said supply and said discharge and for disconnecting both said passages together from said supply and discharge; a safety valve connected with the space above said piston, a clutch operatively connected with said reciprocating mechanism, and means operatively connected with safety valve for throwing out said clutch.

2. A power press comprising a slide, mechanical means for reciprocating said slide, a die, a.

cylinder in said slide, a piston adapted to reciprocate in said cylinder, a tool secured to said piston so as to partake in its reciprocation, said cylinder having apassage at its upper and at its lower end, means for displacing said tool and for fixing it in a given "position with respect to said slide and including: a fluid supply, a fluid discharge, mechanism for. alternately connecting it out when excited, a circuit connected with said electromagnet, and means operatively connected with said safety valve for closing said circuit when said valve opens.

3. A power press comprising a slide, mechanical means for reciprocating said slide, a die, a cylinder in said slide, a piston adapted to reciprocate in said cylinder, a tool secured to said piston so as to partake in its reciprocation, said cylinder having a passage at its upper and at its lower end, means for displacing said tool and for fixing it in a given position with respect to said slide and including: a fluid supply, a fluid discharge, mechanism for alternately connecting one of said passages with said supply and said discharge and for disconnecting both said passages together from said supply and discharge; a safety valve connected withthe space above said piston, a clutch operatively connected with said reciprocating mechanism, a weighted lever adapted to throw out said clutch, a detent operatively connected with said lever, and means operatively connected with said safety valve for throwing out said detent when said safety valve opens.

4. A power press comprising aslide, mechanical means for reciprocating said slide, a die, a cylinder in said slide, a piston adapted to reciprocate in said cylinder, 9. tool secured to said piston so as to partake in its reciprocation, said cylinder having a passage at its upper and at its lower end, means for displacing said tool and for fixing it in a given position with respect to said slide and including: a fluid supply, a fluid discharge, and a four-way valve for alternately connecting one of said passages with said supply and said discharge and for disconnecting both said passages together from said supply and discharge.

5. A power press comprising a slide, mechanical means for reciprocating said slide, a die, a' cylinder in said slide, a piston adapted to reciprocate in said cylinder, a tool secured to said pis-* disconnecting position, and automatic means for returning it into the position in which it connects said upper passage with said fluid supply, and said lower passage with said discharge.

KARL KECK. 

